The present invention relates to an automatic vehicular velocity controlling system and method having such an inter-vehicle distance controlling function as controlling a vehicular velocity to maintain an appropriate inter-vehicle distance.
An European Patent Application First Publication No. EP 0 982 172 A2 published on Mar. 1, 2000 exemplifies a previously proposed automatic vehicular velocity controlling system.
A U.S. Pat. No. 5,959,572 issued on Sep. 28, 1999 also exemplifies another previously proposed automatic vehicular velocity controlling system.
In such a previously proposed automatic vehicular velocity controlling apparatus as described in the above-described European Patent Application First Publication, a vehicular velocity of an automotive vehicle in which the above-described vehicular velocity controlling system is mounted (hereinafter, also referred to as a host vehicle) is controlled so as to provide one of a target vehicular velocity to maintain the inter-vehicle distance and a set vehicular velocity whose magnitude is smaller than the other and so as to maintain the vehicular driver""s set vehicular velocity and so as to maintain the vehicular driver""s set vehicular velocity in a case where no preceding vehicle running ahead of the vehicle is present.
Then, when the vehicular driver operates a coast switch to reduce the set vehicular velocity when operated or an accelerate switch (ACC switch) to increase the set vehicular velocity when operated, the set vehicular velocity is varied by a predetermined velocity so that the vehicular velocity is varied by a predetermined velocity so that the vehicular velocity is controlled by a predetermined vehicular velocity variation rate (viz., by a predetermined acceleration or deceleration) with the set vehicular velocity after the added predetermined vehicular velocity variation rate as a new target vehicular velocity.
Since, in the previously proposed automatic vehicular velocity controlling system, an inter-vehicle distance control and a vehicular velocity control are combined to control the vehicular velocity, an actual vehicular velocity is not always coincident with the set vehicular velocity.
For example, in a case where the target vehicular velocity to maintain a predetermined inter-vehicle distance is smaller in magnitude (viz. lower) than the driver""s set vehicular velocity, the actual vehicular velocity is controlled to become coincident with the target vehicular velocity.
Hence, in a case where the actual vehicular velocity is remarkably different from the set vehicular velocity, a vehicular motion from a time at which the vehicular driver modifies the set vehicular velocity up to a time at which the actual vehicular velocity converges to the set vehicular velocity often does not match with the driver""s sense of driving, viz., the driver often gives an insufficient feeling to the host vehicle.
For example, suppose that, in a case where the host vehicle is running at the actual vehicular velocity of 80 Km/h even with the set vehicular velocity of 100 Km/h because the preceding vehicle is present and the inter-vehicle distance control is activated, the driver operates the coast switch to try to decelerate the vehicle since the host vehicle approaches a toll gate so that the set vehicular velocity is reduced to 70 Km/h.
In this supposition, although the set vehicular velocity is remarkably modified from 100 Km/h to 70 Km/h, the actual vehicular velocity is slightly reduced from 80 Km/h to 70 Km/h.
In addition, since, in a case where no preceding vehicle is present, the actual vehicular velocity is controlled at 100 Km/h if the set vehicular velocity is 100 Km/h. In this case, if the set vehicular velocity s remarkably modified. In such a case as described above, the vehicular velocity is modified by a constant acceleration/deceleration.
In the former case where the slight deceleration is needed, the deceleration is too large. In the latter case when the remarkable deceleration is needed, it takes a lot of time to the time at which the vehicular velocity is converged to the set vehicular velocity.
It is therefore an object of the present invention to provide automatic vehicular velocity controlling system and method capable of performing a vehicular velocity control without insufficient feeling given by the vehicular driver, i.e., which matches with the driver""s sense of driving even if the set vehicular velocity is different from the actual vehicular velocity.
According to one aspect of the present invention, there is provided an automatic vehicular velocity controlling system for an automotive vehicle, comprising; a vehicular velocity controlling command value determining section that selectively determines a vehicular velocity controlling command value from one of a first set vehicular velocity based on an inter-vehicle distance control for a preceding vehicle which is running ahead of the vehicle and a second set vehicular velocity based on a manual setting depending upon a magnitude of which one is smaller than the other and depending upon whether the preceding vehicle is present; a vehicular drive controlling section that drivingly controls one of a vehicular engine, a vehicular transmission, and a vehicular brake system to make an actual vehicular velocity substantially equal to the vehicular velocity controlling command value; a vehicular velocity controlling vehicular velocity command value modification determining section that determines whether a modification of the vehicular velocity controlling command value to a new one is made; and a vehicular velocity command value variation rate determining section that determines a deviation between the new vehicular velocity command value and the actual vehicular velocity and determines a variation rate for the vehicular velocity to reach to the new vehicular velocity command value when the vehicular velocity command value modification determining section determines that the modification is made in such a manner that as a magnitude of the deviation becomes larger, the variation rate becomes larger and as the magnitude of the deviation becomes smaller, the variation rate becomes smaller.
According to another aspect of the present invention, there is provided. An automatic vehicular velocity controlling method for an automotive vehicle, comprising; selectively determining a vehicular velocity controlling command value from one of a first set vehicular velocity based on an inter-vehicle distance control for a preceding vehicle which is running ahead of the vehicle and a second set vehicular velocity based on a manual setting depending upon a magnitude of which one is smaller than the other and depending upon whether the preceding vehicle is present; drivingly controlling one of a vehicular engine, a vehicular transmission, and a vehicular brake system to make an actual vehicular velocity substantially equal to the vehicular velocity controlling command value; determining whether a modification of the vehicular velocity controlling command value to a new one is made; and determining a deviation between the new vehicular velocity command value and the actual vehicular velocity and determines a variation rate for the vehicular velocity to reach to the new vehicular velocity command value when the vehicular velocity command value modification determining section determines that the modification is made in such a manner that as a magnitude of the deviation becomes larger, the variation rate becomes larger and as the magnitude of the deviation becomes smaller, the variation rate becomes smaller.
This disclosure of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.